The Mobile Auth and SMS protect (mobile phone messaging service) used to be totally separate. So it was true that you did not need a phone number to use the Mobile Auth, just a device that could run it.
Recently that changed and you need an eligible phone number even for the Auth. This of course creates issues because pre-paid numbers, or VOIP numbers are not eligible. Worse, some numbers are flagged as pre-paid when they no longer are. Cricket seems to fall into that bucket a lot. Blizz cant change the flagging and the phone provider usually can’t either.
The keychain version of the Authenticator is no longer sold so that is not a work around either.
It means fewer people have access to the Mobile Auth now - and with the elimination of the keychain version, it is a step in the wrong direction for security accessibility - in my opinion.
They sent you to the forums because that is how Blizzard wants feedback and suggestions submitted. CS can’t serve as a vector for it.
Note: MVPs are other players not Blizzard employees. MVPs do not represent or speak for Blizzard.